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Large-scale hot air drying rooms play a crucial role as efficient drying equipment across various industries. The uniform distribution of hot air is a crucial factor influencing the drying quality of large-scale hot air drying rooms. This study focuses on camellia seeds as the drying subject. Building on a porous media model and the drying kinetics of camellia seeds, a CFD model of the drying room was established. Three-dimensional simulations of the internal flow and temperature fields were performed using CFD software, and the simulated results aligned well with experimental data. To improve the uniformity, this study introduced an optimized design featuring a combination of a Type E3 air guide hood with five guiding plates and a fan, selected based on optimized angles (θ1 = 5°, θ2 = 10°). Under the condition of improving the structure without introducing a new heat source, the optimization ensured a significant improvement in flow field uniformity while making the temperature field closer to the desired ideal temperature. This offers a reference for the design and research of hot air drying equipment and hot air drying rooms. [ABSTRACT FROM AUTHOR]

A CFD code is programmed to simulate the drying process of gypsum board with hot air in a 2D computational domain. The Realizable k − ε model is used to model turbulent behavior in the flow field. The influence of air velocity, temperature, dryer geometry structure in this process has been investigated. This study was performed to configure operating temperatures (303, 333, 353, 373 K) and air velocities (5, 10, 15 m/s). By examining several operating conditions and their effects, it is better to obtain the optimal state for the drying process according to the operating conditions. Among the studied cases (for different temperatures), about 95% improvement is achieved in the computational range(between the lowest temperature and speed compared to the highest temperature and speed) for drying rate. Different drying zone geometries (13 geometries) with different shapes of baffles were studied to find out if there was any improvement on airflow in the gypsum-board drying process. Results showed that baffles with large longitudinal vortices could help the gypsum board to be dried with controlled drying rate. Changes in velocity and moisture on the surface for the best form of simulated baffles compared to without baffles geometry were 85.30% and 34.68%, respectively. [ABSTRACT FROM AUTHOR]

With buildings representing a substantial portion of global energy consumption, exploring alternatives to traditional fossil fuel-based heating and cooling systems is critical. Thermoelectricity offers a promising solution by converting temperature differentials into electrical voltage or vice versa, enabling efficient indoor thermal regulation. This paper presents a comprehensive investigation into the integration of thermoelectric wall systems for sustainable building climate control through numerical simulations and experimental analyses. Numerical simulations using computational fluid dynamics (CFD) techniques were conducted to model fluid flow and heat transfer within the thermoelectric wall systems under various operating conditions. These simulations provided insights into the system's thermal behavior, which were validated through experimental setups designed to measure temperature differentials, airflow rates, and power consumption. The results showed that power consumption is directly correlated with electrical current, ranging from 0.19 W to 77.4 W as the current increased from 0.1 A to 2 A. Additionally, the heat absorbed by the system increased significantly with electrical current, by 706–1044%, depending on the air velocity. The thermal energy released from the hot side of the thermoelectric modules also rose substantially, ranging from 9850 to 5285% with increasing electrical current, and from 275 to 51% with higher air velocities. Moreover, increasing air velocity led to a 6.78–9.37% reduction in power consumption for currents between 0.1 A and 2 A. The coefficient of performance (COP) analysis revealed that optimizing both electrical current and air velocity is essential for maximizing system efficiency. While fan power consumption reduces COP at higher air velocities, neglecting fan power consumption results in COP improvements ranging from 6.5 × 10⁻⁴ to 49.0%. These findings highlight the potential of thermoelectric wall systems to enhance indoor comfort and energy efficiency in buildings. [ABSTRACT FROM AUTHOR]

Due to the complexity of the internal pore structure of petroleum coke loose particle‐packed beds, measuring their thermal conductivity has always been a challenging problem. This work independently developed an experimental apparatus for testing the thermal conductivity of petroleum coke particle‐packed beds and constructed a forward calculation model for the heat transfer process, which was based on one‐dimensional unsteady heat transfer. Using the Sparse Nonlinear OPTimizer (SNOPT) algorithm, a mathematical relationship between the thermal conductivity λ of the coke bed, temperature T, and equivalent particle diameter dp was established through inverse modeling. Concurrently, a digital model of the petroleum coke particle packed bed was derived utilizing three‐dimensional computed tomography (CT) scanning technology, and a pore‐scale gas–solid radiation heat transfer model was formulated based on CFD simulation technology, thereby further elucidating the heat transfer mechanism within the petroleum coke particle packed bed. The research results indicate that the temperature predicted by the established thermal conductivity model aligns well with experimental data. Further CFD simulation studies demonstrate that a smaller particle size leads to a larger temperature difference between the wall and the center of the packed bed, while a higher gas velocity results in a smaller temperature difference, with a linear correlation observed between these two factors. At high temperatures, thermal radiation between particles in the porous petroleum coke‐packed bed plays a dominant role. The research outcomes can offer significant theoretical support for a profound analysis of the heat transfer behavior of petroleum coke‐packed beds within a vertical shaft calciner. [ABSTRACT FROM AUTHOR]

The optimization of Venturi mixers in burners is critical for enhancing combustion efficiency and minimizing emissions. In this study, we utilize the adjoint method to analyze and refine the design of a Venturi mixer. Our numerical simulations integrate the species transport equation with the eddy dissipation model (EDM) for reacting flow and the generalized k- (GEKO) model to simulate turbulence. By solving adjoint equations, we effectively compute the shape sensitivity for various observables, including pressure drop, outlet fuel variance/uniformity deviation index, air and fuel mass flow rates, and outlet CO mass fraction. The shape sensitivity analysis uncovers the interplay between the observables and the appropriate weights for multiple objective optimizations. Subsequently, we perform gradient-based optimizations to enhance the mixer's performance, employing both shape sensitivity and mesh morphing techniques. We conduct a series of case studies focusing on both cold and reacting flows. The optimization of cold flow provides an in-depth exploration of various optimization strategies, encompassing single-objective and multi-objective optimization with diverse weight combinations. Following this, the optimization under reacting flow conditions improves the fuel/air mixing, leading to the increase of combustion efficiency and hence the reduction of CO emissions. Our findings showcase the potential of an adjoint-based optimization framework in designing Venturi mixers that are efficient and emit lower levels of pollutants. [ABSTRACT FROM AUTHOR]

The information of the degree of blade erosion is vital for the efficient operation of steam turbines. However, it is nearly impossible to directly measure the degree of blade erosion during operation. Moreover, collecting sufficient data of eroded cases for predictive analysis is challenging. Therefore, this paper proposes a blade erosion prediction method using numerical simulation and machine learning. Pressure data of several blade erosion cases are collected from the numerical turbine simulation. The machine learning approach involves training on collected simulation data to predict the degree of erosion for the first-stage stator (1S) and the first-stage rotor blade (1R) from internal pressure data. The proposed erosion prediction model employs a two-step hierarchical approach. First, the proposed model predicts the 1S erosion degree using the k-nearest neighbor (k-NN) regression. Second, the proposed model estimates the 1R erosion degree with linear regression models. These models are tailored for each of the 1S erosion degrees, utilizing pressure data processed through fast Fourier transform (FFT). The evaluation shows that the proposed method achieves the prediction of the 1S erosion with a mean absolute error (MAE) of 0.000693 mm and the 1R erosion with an MAE of 0.458 mm. The evaluation results indicate that the proposed method can accurately capture the degree of turbine blade erosion from internal pressure data. As a result, the proposed method suggests that the erosion prediction method can be effectively used to determine the optimal timing for maintenance, repair, and overhaul (MRO). [ABSTRACT FROM AUTHOR]

The present case study focuses on indoor radon dispersion in an experimental room made of unfired mud brick by employing CFD modeling, active measurement, and passive measurement in closed and open room conditions. Radon flux for walls and floor surfaces of the room was measured experimentally. A CFD model was designed to simulate spatial distribution pattern of indoor radon. The CFD simulation results are validated through a newly developed RnDuo monitor and single-entry pinhole-based twin-cup dosimeter. The mean indoor radon concentration decreases by approximately one-fourth level in an open room as compared to a closed room. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper explores the reasons for the perforation failure of the shale gas gathering pipeline in the E Gas Mine and proposes preventive measures. EDS experiment found that the corrosion products were mainly Fe2O3, FeS, and FeCO3. Shale gas contains 24.908 g/m3 CO2 and 0.384 g/m3 H2S, and formation water contains 20.445 g/m3 Cl−. Therefore, CO2/H2S corrosion has occurred in the pipeline, and Cl− exacerbated localized damage to the material matrix, accelerated corrosion of the pipeline. The base material was more corrosion resistant than the weld, but the weld was more erosion resistant than the base material. The CFD simulation results found that the main reason of pipeline erosion is that, the shale gas contains grit and the gas volume exceeds the designed gas volume. So, the perforation failure of the pipeline was a result of both corrosion and erosion, and the effect of erosion is stronger than that of CO2/H2S corrosion on the pipeline. [ABSTRACT FROM AUTHOR]

We evaluate the thermal performance of PUF-insulation boards embedded in the roof of an office-sized room. Two rooms were constructed: one with and the other without insulation. The thermal comfort was evaluated by performing an experimental study according to ANSI/ASHRAE Standard 55-2017. The inside air temperature, humidity, wall and ceiling temperatures, air velocities and thermal flux were measured for the summer April–June 2023. Using these measurements, the PMV and PPD values were computed. The effectiveness of the insulation material with regard to thermal comfort is judged by the reduction in values of these indices. During a typical day, a reduction of around 30% is achieved just by adding the insulation. Nusselt number correlations are proposed to predict the convective heat transfer from the walls. Detailed CFD simulations were performed and a parametric study to understand the effect of insulation thickness, wall insulation, roof thickness and room dimensions on thermal comfort was undertaken. [ABSTRACT FROM AUTHOR]

The black-water regulating valve is very easy to be damaged due to the erosion of the key components, such as valve spool and valve seat. This work presents the failure analysis of the spool and seat of regulating valve in the black-water treatment system. Scanning electron microscopy and X-ray energy-dispersive spectrometer were used to detect the morphology and chemical compositions of failure valve samples. The computational fluid dynamics method was also adopted to simulate the medium flow characteristics in black-water regulating valve. The results show that most erosion areas of the valve occur at the spool-seat throttle zone. The erosion profile is mainly manifested in plastic deformation pits, cutting abrasions, furrows, pinhole pits and impact pits. The particles and cavitation bubbles move toward the throttle zone driven by black-water medium, causing particles impact and bubbles collapse. The particle flow velocity in the throttle zone of the valve is between 50 and 175 m/s, while the maximum velocity can reach 175 m/s. The valve suffered severe particle erosion and cavitation erosion under the particle impact and bubble collapse, finally resulting in its failure. [ABSTRACT FROM AUTHOR]

An air-rock bed thermal storage system was designed for small-scale powered generation and analyzed with computational fluid dynamics (CFD) using ANSYS-Fluent simulation. An experimental system was constructed to compare and validate the simulation model results. The storage unit is a cylindrical steel container with granite rock pebbles as a storage medium. The CFD simulation used a porous flow model. Transient-state simulations were performed on a 2D axisymmetric model using a pressure-based solver. During charging, heat input that keeps the bottom temperature at 550 °C was applied to raise the storage temperature. Performance analysis was conducted under various porosities, considering natural and forced convection. The natural convection analysis showed insignificant convection contribution after 10 h of charging, as observed in both average air velocity and the temperature profile plots. The temperature distribution profiles at various positions for both convection modes showed good agreement between the simulation and experimental results. Additionally, both cases exhibited similar temperature growth trends, further validating the models. Forced convection reduced the charging time from 60 h to 5 h to store 70 MJ of energy at a porosity of 0.4, compared to natural convection, which stored only 50 MJ in the same time. This extended charging period was attributed to poor natural convective heat transfer, indicating that relying solely on natural convection for thermal energy storage under the given conditions is not practical. Using a small fan to enhance heat transfer, forced convection is a more practical method for charging the system, making it suitable for power generation applications. [ABSTRACT FROM AUTHOR]

Achieving high fluidization quality and bed stability is a paramount challenge in pulsed fluidized beds. 2D hydrodynamics models were studied using the Eulerian-Eulerian method with KTGF. This study investigates the impact of rectangular pulsation superimposed on steady airflow, while maintaining a constant temporal average gas velocity, on fluidization quality. Numerical results indicated that superimposing pulsations on steady airflow and increasing the steady airflow velocity to three times the minimum fluidization velocity resulted in a decrease in the bed expansion ratio. This decrease was most notable particularly at a pulsation frequency of 0.05Hz, with a reducing of approximately by about 21%. By decreasing the velocity ratio from 9.52 to 6.52, the pressure drop increased by 27% and 4.5% at 0.05 Hz and 10 Hz, respectively. Additionally, the fluidization index increased by 32% and 2% under these conditions. The optimal range of pulsed airflow velocity fell between 2.76 and 1.17 times the steady airflow velocity and was most effective at 0.05 – 0.1 Hz. [ABSTRACT FROM AUTHOR]

In dental clinics with an open floor plan, the risk of patient-to-patient transmission of respiratory disease is a concern. During dental procedures large amounts of bioaerosol are produced and patients cannot wear personal protective equipment. This paper examines how to effectively deploy air cleaner to reduce the infection risk in dental clinics with an open floor plan. Various locations of air cleaners at various clean air delivery rates (CADRs) were investigated. The dispersion of bioaerosol was studied through numerical simulations, and risk assessment was performed by a dose-response method. The findings indicated that dental patients downstream of the background ventilation have a higher infection risk than those to the left and right of an infected patient (i.e., the source). The lowest infection risks for the adjacent patients were found when the air cleaner was place opposite to the dentists, i.e., on the floor at low CADR levels of 2.2 m3/min or on the bench at CADR levels of 4.4 m3/min or greater. The results of this study indicated that air cleaner can mitigate the risk of patient-to-patient transmission of SARS-CoV-2 in dental clinics with an open floor plan. Background CADR levels determine the optimal placement of air cleaners. [ABSTRACT FROM AUTHOR]

To accurately predict the film thickness distribution during dynamic spraying performed with air guns and support accordingly the development of intelligent spray painting, the spray problem was analyzed numerically. In particular, the Eulerian-Eulerian approach was employed to calculate the paint atomization and film deposition process. Different spray heights, spray angles, spray gun movement speeds, spray trajectory curvature radii, and air pressure values were considered. Numerical simulation results indicate that the angle of spray painting significantly affects the velocity of droplets near the spray surface. With an increase in the spraying angle, spraying height and spray gun movement speed, the maximum film thickness decreases to varying degrees, and the uniformity of the film thickness also continuously worsens. When the spray gun moves along an arc trajectory, at smaller arc radii, the film thickness on the inside of the arc is slightly greater than that on the outside, but the impact on the maximum film thickness is minimal. Increasing air pressure expands the coating coverage area, results in finer atomization of paint droplets, and leads to a thinner and a more uniform paint film. However, if the pressure is too high, it can cause paint splattering. Using the orthogonal experimental method, multiple sets of simulation calculations were conducted, and the combined effects of spraying height, spray angle, and spray gun movement speed on the film thickness distribution were comprehensively analyzed to determine optimal configurations. Finally, the reliability of the numerical simulations was validated through dynamic spray painting experiments. [ABSTRACT FROM AUTHOR]

Improving the overall energy efficiency of thermodynamic cycles relies heavily on the replacement of traditional pure fluids with zeotropic mixtures. The selection of the optimal components within the zeotropic mixture depends on the specific operating conditions of the thermodynamic cycle. Therefore, significant enhancements in performance can be achieved across varying operating conditions by effectively controlling the composition of zeotropic mixtures in the cycle. According to the gas-liquid equilibrium characteristics of the zeotropic mixtures, the adjustment of the medium components and the boundary conditions can be realized if the components can be adjusted through the gas-liquid separation. In this study, a novel device is proposed for automatically regulating the speed of gas-liquid separation in order to separate the components of the zeotropic mixtures. The CFD simulation was utilized to analyze the structural parameters and boundary conditions that impact the efficiency of gas-liquid separation. The results indicate that the adjustable mass flow range of the optimal structure is broadened by 5.5 times compared to conventional gas-liquid separation devices, ranging from 0 kg/s to 0.15 kg/s. Additionally, within this range, the gas-liquid separation efficiency exceeds 95%, representing a 10% improvement over traditional phase separators. [ABSTRACT FROM AUTHOR]

In air conditioning systems, air curtains play a crucial role in reducing the exchange of hot and cold air between the interior and exterior environments. Nevertheless, the majority of current air curtains suffer from limited airtightness and real-time performance due to their complex jet trajectory, relying on traditional control methods. Thus, this paper introduces an angle control algorithm for air curtains based on a GA-optimized quadratic BP neural network. Initially, the BP neural network is trained using the Hayes dataset to develop the prediction model for temperature-jet angle. Subsequently, the optimization model for jet angles-windshield angle is constructed, and the optimal angles set meeting the fitness function is identified using GA global search. Later, the prediction model and the optimal angles set are once again trained using the BP neural network to generate prediction model for temperature-jet angles and windshield angle. Following CFD simulation, the airtightness indicator demonstrated a 26.5% improvement with the proposed control method compared to traditional ones, highlighting the superior airtightness. In comparison to other algorithms, the proposed algorithm demonstrates a remarkable 89% enhancement in real-time performance and stronger robustness. This study presents a novel approach for the intelligent control of air curtains, holding significant importance in advancing the intelligent development of air curtain technology and facilitating energy efficiency and emission reduction. [ABSTRACT FROM AUTHOR]

Double-wire arc welding involves simultaneously feeding two wires into a molten pool, improving the efficiency and flexibility of traditional welding techniques. However, the interactions between the two wires and the molten pools are complex, which increases the difficulties in process and composition control. This work focuses on the weld pool flow characteristics in double-wire TIG arc welding. A CFD model incorporating a liquid bridge transfer model was developed to simulate the fluid flow phenomenon. Results show that the bead-forming appearances and flow characteristics of double-wire arc welding show no significant differences from single-wire arc welding. Welding current and welding speed have significant effects on the weld bead dimensions, while only welding current has effects on the flow characteristics. Wire feed XOZ angles show no significant influences on weld bead forming appearances and molten pool flow characteristics. Wire feed XOY angles influence the symmetry of the weld bead and the fluid flow. In 5B71/7055 heterogeneous double-wire arc welding, achieving a uniform distribution of alloy elements is difficult due to the complex convection patterns within the molten pool. [ABSTRACT FROM AUTHOR]

In a polymer electrolyte membrane (PEM) fuel cell, the following degradation mechanisms are associated with the catalyst particles and their support: carbon support corrosion triggered by carbon and platinum oxidation, platinum dissolution with redeposition, and particle detachment with agglomeration. In this work, an electrochemical model for those degradation effects is presented as well as its coupling with a three‐dimensional computational fluid dynamics PEM fuel cell performance model. The overall model is used to calculate polarization curves and current density distributions of a PEM fuel cell in a fresh and aged state as well as the degradation process during an accelerated stress test with 30 000 voltage cycles. The obtained simulation results are compared to measurements on a three‐serpentine channel PEM fuel cell with an active area of 25 cm2 under various temperatures and humidities. The experimental data are obtained with a segmented test cell using respective degradation protocols and test conditions proposed by the United States Department of Energy. In addition to the temperature and humidity changes, the influence of geometry and material parameters on the degree of degradation and the resulting fuel cell performance is explored in detail. [ABSTRACT FROM AUTHOR]

The demand for clean and sustainable energy has led to the exploration of innovative technologies for renewable energy generation. The Savonius turbine has emerged as a promising solution for harnessing wind energy in urban environments due to its unique design, simplicity, structural stability, and ability to capture wind energy from any direction. However, the efficiency of Savonius turbines poses a challenge that affects their overall performance. Extensive research efforts have been dedicated to enhancing their efficiency and optimizing their performance in urban settings. For instance, an axisymmetric omnidirectional deflector (AOD) was introduced to improve performance in all wind directions. Despite these advancements, the effect of wind incident angles on Savonius turbine performance has not been thoroughly investigated. This study aims to fill this knowledge gap by examining the performance of standard Savonius configurations (STD) compared to the basic configuration of the deflector (AOD1) and to the optimized one (AOD2) under different wind incident angles and wind speeds. One key finding was the consistent superior performance of this AOD2 configuration across all incident angles and wind speeds. It consistently outperformed the other configurations, demonstrating its potential as an optimized configuration for wind turbine applications. For instance, at an incident angle of 0°, the power coefficient of the configuration of AOD2 was 61% more than the STD configuration. This ratio rose to 88% at an incident angle of 20° and 125% at an incident angle of 40°. [ABSTRACT FROM AUTHOR]

The two‐fluid model–kinetic theory of granular flow (TFM–KTGF) model and the sub‐grid‐scale (SGS) model are used to conduct a three‐dimensional numerical simulation study on the hydrodynamic characteristics of a two‐stage fluidized bed with an integrated overflow pipe. Using various drag models, the gas–solid flows, bed expansions, pressure drop distributions, and equilibrium conditions in the two‐stage bed are compared, and the conditions for the formation of a stable overflow in the two‐stage bed are thoroughly investigated. In addition, during the simulation of the secondary distribution in the bed, the porous media model simulates the momentum loss caused by the redistribution plate to avoid the direct simulation of the redistribution plate, which requires extensive grid division work and calculation costs. This work can provide technical direction for the industrialization of one‐step coal to multistage fluidized bed natural gas technology. [ABSTRACT FROM AUTHOR]

A detailed computational investigation was conducted to explore the dynamics of high-speed free slurry jets, with a focus on how variations in abrasive size and concentration affect their behavior. The study yielded several significant observations: Firstly, it was observed that slurry jets containing larger particles exhibited notably higher average velocities, attributed to their inherent self-similar characteristics. Specifically, at the far field of the jet, slurry jets with larger particle sizes demonstrated a 15% increase in velocity compared to those with smaller particles. Additionally, an analysis of turbulent intensity revealed that beyond a certain axial distance (x/D = 10), turbulence levels progressively increased. However, intriguingly, for slurry jets with a high concentration (Co = 15%), there was a notable decrease (28%) in turbulent intensity compared to water jets, indicating a complex interplay between particle size and concentration. Secondly, the study found that as the concentration of particles in the slurry jet increased, there was a corresponding rise in the bulk temperature of the jet. This phenomenon was primarily attributed to the heightened thermal conductivity resulting from the increased density of particles in the water. Furthermore, an examination of the Nusselt number revealed interesting trends. While the Nusselt number exhibited a peak near the nozzle exit, indicative of enhanced heat transfer in this region, it showed a decremental trend along the axial direction of the jet, attributable to jet divergence. In summary, the computational analysis provided valuable insights into the behavior of high-speed slurry jets, highlighting the intricate relationships between abrasive size, concentration, velocity distribution, and thermal characteristics. These findings contribute to a deeper understanding of slurry jet dynamics and have significant implications for various industrial applications. [ABSTRACT FROM AUTHOR]

Severely cold weather reduces the willingness of residents to open windows while cooking. This results in an insufficient replenishment of makeup air and a reduction in the range hood discharge capacity. For an effective trade-off between indoor air temperature maintenance and air quality aggravation in winter, a new makeup air supply method (ceiling makeup air) was proposed and established both experimentally and numerically. The improvements in the kitchen air environment during cooking were studied through experimental tests and CFD simulations, considering different makeup air arrangements. The results reveal that the ceiling makeup air scheme can significantly reduce the concentration of PM2.5 compared with the cracks makeup air scheme (wherein the kitchen window and door are closed). Moreover, it increased the indoor temperature by over 11.9 °C compared with the open window makeup air scheme. The average relative error between the experimental and simulated data was within 6.1%. Among the considered factors, the size of the air inlet had the largest impact. This was followed by the layout, size, and shape of the ceiling inlets. The ceiling makeup air scheme demonstrated the potential for improving residential kitchen air environments in severely cold regions. [ABSTRACT FROM AUTHOR]

When loading liquefied natural gas (LNG) onto a dual-fuel LNG container ship fuelled by LNG, there is a considerable temperature difference between LNG and the fuel tank at room temperature. The current solution is to pre-cool the tank with LNG through a spray line but the cooling process, if not correctly handled, can result in excessive cooling rates and Boil-Off Gas (BOG), which can expose the tank to increased temperature stress and gas pressure. Therefore, this paper takes the Mark III fuel tank of a specific type of LNG container ship as the object and realises a real-time predictive control system by writing a UDF (User Defined Function) to simulate and analyse the influence of LNG spray rate on the change of cooling effect, cooling time and cooling cost under the unidirectional LNG spray cooling mode. Compared with the results of the fuel tank gas experiment, the deviation of numerical model simulation results is less than 5%. Under the same cooling rate, the real-time control scheme can achieve a more uniform cooling rate and reduce the total LNG consumption by 25%. With the increase in LNG cooling rate, the cooling time, LNG usage, and the total BOG exhaust volume all decrease; however, the decreased range gradually decreases as well. The results of this paper provide parameters and suggestions for optimising and improving the LNG fuel tank cooling monitoring and control system. [ABSTRACT FROM AUTHOR]

With the ability to manufacture complex functional structures, Additive Manufacturing (AM) enables new advanced applications which could not be realized before. An example of such structures is open porous structures. In the presented approach, the open porous structures are a result of the selected manufacturing parameters, instead of being defined in CAD models. Thereby, various porosities can be achieved flexibly without design adjustments. However, to comprehensively understand the correlation of manufacturing parameters and different properties, various tests are required. As an alternative, properties can be determined by means of simulation. This study presents 3D reconstructions of complex open porous structures, which are based on μ-CT imaging. The influence of the downsampling during voxelization on the 3D reconstructed geometry is studied. Further, different polyhedral mesh settings have been tested in order to find a mesh that minimizes the deviation between the CFD simulation results and the laboratory test results for flow resistance. A guideline for the creation of a calibrated CFD model based on μ-CT imaging is proposed. As it is acknowledged by the authors that the data availability to reconstruct shown cases is crucial, data for a reference case have been made freely available online. [ABSTRACT FROM AUTHOR]

Summary: As one of major construction facilities, the safety concern about elevator outer‐attached to slender high‐rise buildings during construction needs to be seriously addressed. To specifically identify the risk of such slender building–elevator systems in extreme tornado wind field, a safety assessment strategy using the critical velocity envelope is systematically developed. To overcome the difficulties in modeling such building–elevator system, a modified generalized flexural‐shear model developed previously was employed to reach an efficient estimate on the response of a case high‐rise building under simulated tornado wind excitations. To account for the effect of the flexibility of high‐rise building on the response of its attached construction elevator, the response of the elevator was obtained by finite element analysis with applied wind forces, as well as the displacement excitations at its supports with the building. To simulate the typical failure modes of elevator in all states, some critical reference velocity‐based envelopes were generated for the safety assessment where the factors of wind velocity, wind direction, and cage level are systematically addressed. The safety envelopes of the building–elevator system were proved to be instinctively efficient for the assessment of its wind resistance under various scenarios. [ABSTRACT FROM AUTHOR]

The performance of continuous feeding fluidized bed reactors is significantly influenced by their design. These reactors can effectively operate with a wide range of biomass mixtures. Therefore, it is imperative to carefully design the gas distributor plate and solid tube inlet to ensure stable fluidization and uniform distribution of fluidizing gas and solid particles within the reactor. This study investigated the impact of gas–solid feeder design in bubbling fluidized bed gasifier for biomass mixtures on system hydrodynamics, employing a computational fluid dynamics–artificial neural network (CFD‐ANN) coupling model to achieve more realistic simulations. A 2k factorial experimental design was adopted to inquire the impact of gas and solid feeding systems. The responses under investigation included the gas–solid mixing index and the solid residence time, both of which hold pivotal roles in specific chemical processes related to biomass utilization in fluidized bed technology. All cases were successfully simulated, and the results uncovered that the position and length of the solid inlet tube wielded a significant influence on reactor performance, particularly concerning solid residence time. Furthermore, the designs of the gas distributor were identified as critical factors capable of enhancing system turbulence and mixing. In summary, the results showed the potential for enhancing reactor performance through the optimization of gas–solid feeding systems and underscored the efficacy of the ANN drag model in simulating continuous biomass gasification systems. [ABSTRACT FROM AUTHOR]

Refractory materials are used worldwide in process equipment. However, gaseous and liquid process products penetrate the surface layer and deep into the volume of refractories, destroying rather expensive constructions that are complicated to repair. To address this challenge, there is a need to develop protective coatings for refractory materials that can limit the penetration of working media and extend their operational lifespan. In this work, the application of gas-dynamic cold spraying (CGDS) to produce a coating on the refractory materials using fine titanium dioxide (TiO2) particles is explored. These particles are accelerated within a nitrogen flow, passing through a Laval nozzle, and then sprayed onto a fireclay surface. The mechanisms of particle deposition and layer formation on porous surfaces through experiments and numerical simulations were investigated. The geometry of a typical refractory pore was determined, which was then incorporated into computational fluid dynamics (CFD) simulations to model the cold spraying process of porous substrates. As a result, the influence of the particle size on its velocity and angle of penetration into pores was established. Experimental findings demonstrate the effective closure of pores and the formation of a particle layer on the refractory surface. Furthermore, the nanoindentation tests for the refractory samples showcase capabilities for checking coating thickness for porous materials. [ABSTRACT FROM AUTHOR]

In the context of increasing global energy shortages and climate change, the human living environment, as a crucial component of residents' daily lives, has garnered growing attention from the academic community. Research on residential environments is vital for promoting the sustainable development of urban construction and constitutes an important aspect of sustainable development studies. This study focuses on the optimization strategy for the outdoor activity space wind environment in the Xihuayuan residential area in Lanzhou city, utilizing spatial syntax analysis and Computational Fluid Dynamics (CFD) simulation technology. Firstly, the outdoor activity space is analyzed for visibility and spatial accessibility using DepthmapX0.6 software. Then, the outdoor wind environment in the residential area is simulated using PHOENICS 2018 software, and the analysis is conducted on outdoor spaces with a poor wind environment in terms of high accessibility. The results indicate that residents' outdoor comfort in these spaces is poor, highlighting the urgent need for improvement in the wind environment. This research attempts to optimize the wind environment in high-accessibility spaces within the residential area by improving building layout, orientation, and height. The simulation results after optimization demonstrate an increase in the overall average wind speed to 1.44 m/s, with the proportion of spaces with a good wind environment in high-accessibility areas during summer rising from 33.4% to 59.2%. The optimization strategy effectively improves the wind environment in high-accessibility areas of the residential area. [ABSTRACT FROM AUTHOR]

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Abstract With buildings representing a substantial portion of global energy consumption, exploring alternatives to traditional fossil fuel-based heating and cooling systems is critical. Thermoelectricity offers a promising solution by converting temperature differentials into electrical voltage or vice versa, enabling efficient indoor thermal regulation. This paper presents a comprehensive investigation into the integration of thermoelectric wall systems for sustainable building climate control through numerical simulations and experimental analyses. Numerical simulations using computational fluid dynamics (CFD) techniques were conducted to model fluid flow and heat transfer within the thermoelectric wall systems under various operating conditions. These simulations provided insights into the system’s thermal behavior, which were validated through experimental setups designed to measure temperature differentials, airflow rates, and power consumption. The results showed that power consumption is directly correlated with electrical current, ranging from 0.19 W to 77.4 W as the current increased from 0.1 A to 2 A. Additionally, the heat absorbed by the system increased significantly with electrical current, by 706–1044%, depending on the air velocity. The thermal energy released from the hot side of the thermoelectric modules also rose substantially, ranging from 9850 to 5285% with increasing electrical current, and from 275 to 51% with higher air velocities. Moreover, increasing air velocity led to a 6.78–9.37% reduction in power consumption for currents between 0.1 A and 2 A. The coefficient of performance (COP) analysis revealed that optimizing both electrical current and air velocity is essential for maximizing system efficiency. While fan power consumption reduces COP at higher air velocities, neglecting fan power consumption results in COP improvements ranging from 6.5 × 10⁻⁴ to 49.0%. These findings highlight the potential of thermoelectric wall systems to enhance indoor comfort and energy efficiency in buildings.

Abstract A detailed computational investigation was conducted to explore the dynamics of high-speed free slurry jets, with a focus on how variations in abrasive size and concentration affect their behavior. The study yielded several significant observations: Firstly, it was observed that slurry jets containing larger particles exhibited notably higher average velocities, attributed to their inherent self-similar characteristics. Specifically, at the far field of the jet, slurry jets with larger particle sizes demonstrated a 15% increase in velocity compared to those with smaller particles. Additionally, an analysis of turbulent intensity revealed that beyond a certain axial distance (x/D = 10), turbulence levels progressively increased. However, intriguingly, for slurry jets with a high concentration (Co = 15%), there was a notable decrease (28%) in turbulent intensity compared to water jets, indicating a complex interplay between particle size and concentration. Secondly, the study found that as the concentration of particles in the slurry jet increased, there was a corresponding rise in the bulk temperature of the jet. This phenomenon was primarily attributed to the heightened thermal conductivity resulting from the increased density of particles in the water. Furthermore, an examination of the Nusselt number revealed interesting trends. While the Nusselt number exhibited a peak near the nozzle exit, indicative of enhanced heat transfer in this region, it showed a decremental trend along the axial direction of the jet, attributable to jet divergence. In summary, the computational analysis provided valuable insights into the behavior of high-speed slurry jets, highlighting the intricate relationships between abrasive size, concentration, velocity distribution, and thermal characteristics. These findings contribute to a deeper understanding of slurry jet dynamics and have significant implications for various industrial applications.

The erosion-corrosion mechanism in rotary flowing seawater is hugely complicated due to the multiscale coupling processes of particle-surface impact, ion mass transfer, and interface electrochemistry. Therefore, developing erosion-corrosion resistant material and exploring the synergistic mechanism between sand erosion and electrochemical corrosion is vital. This study conducted the erosion-corrosion test on Ni2FeCrMo0.2 high-entropy alloy under the particle-seawater flow. Based on a coupled analysis of multi-component weight loss, electrochemical behavior, and microscopic damage morphology, the multiscale coupling processes of sand transportation, particle-surface impact, ion mass transfer, and interface electrochemistry were revealed. The present study found that with the increase of sand size, the energy carried by the particles promoted impact erosion. Additionally, particle movement enhanced ion mass transfer through turbulent effects, and the impact behavior disrupted the passivation film to promote electrochemical processes by reducing the thickness of the passivation film, leading to an increase in the erosion-corrosion rate. However, when the particle size continued to increase to a certain extent, the impact frequency decreased, reducing the erosion-corrosion rate. As the sand size grew, the dominant damage mechanism transitioned from pure corrosion (100 μm) to synergistic effects (200 μm, 400 μm) and then to pure erosion (800 μm). This study provides an in-depth understanding of the erosion-corrosion mechanism in seawater from the perspective of particle-ion-fluid-surface interaction by multi-element characterization.

The effect of water vapor content on the oxidation behavior of In625 at 900 °C in synthetic air was reported. The higher the water vapor content, the greater the oxidation and volatilization rates were. Increasing the water vapor content led to an increase in the proportion of spinel and rutile-type oxides in the oxide scale compared to chromia, and the proportion of Al-rich oxides within the alloy. A kp-kv mass variation model was used to quantify the experimental results, and Fluent Ansys® CFD simulations of the gas phase were used to predict volatilization rates. CFD simulations were used to calculate local gas velocity, temperature and composition along with local volatilization rates at each point on the sample surface. It was possible to explain not only the variations in volatilization between upstream and downstream samples, but also the increased volatilization at sample corners. For longer durations, it was shown experimentally that the rate of volatilization decreases. This was explained by the enrichment of the oxide scale with spinel and rutile-type oxides. [ABSTRACT FROM AUTHOR]

Wind tunnel tests or computational fluid dynamics (CFD) simulations of the aeroelastic model of a bridge deck section are currently used to make sure that significant vortex-induced vibration (VIV) of a long-span bridge will not occur after the bridge is put into operation. However, significant VIV still occurred in several long-span bridges in operation, indicating that the currently used wind tunnel tests and CFD simulations have some drawbacks or uncertainties. This study aims at establishing a digital twin by interacting CFD simulation with wind tunnel test for accurately and efficiently predicting the VIV response of a bridge deck. The measurement information of VIV of the deck section is collected from the wind tunnel test and fused with the CFD simulation. The optimisation for reducing uncertainties existing in wind tunnel test and CFD simulation is then carried out to make the CFD simulation as a digital twin. The digital twin is finally used to investigate the blockage effect of wind tunnel test and give an accurate and efficient prediction of VIV of the bridge deck. The flat closed-box steel deck section used in the Xiangshan Harbor cable-stayed bridge is selected as a case study. The results from the case study show that the digital twin can be established and used for an accurate and efficient prediction of VIV of the bridge deck section. [ABSTRACT FROM AUTHOR]

This paper represents a detailed and systematic review of one of the most ongoing applications of computational fluid dynamics (CFD) in biomedical applications. Beyond its various engineering applications, CFD has started to establish a presence in the biomedical field. Cardiac abnormality, a familiar health issue, is an essential point of investigation by research analysts. Diagnostic modalities provide cardiovascular structural information but give insufficient information about the hemodynamics of blood. The study of hemodynamic parameters can be a potential measure for determining cardiovascular abnormalities. Numerous studies have explored the rheological behavior of blood experimentally and numerically. This paper provides insight into how researchers have incorporated the pulsatile nature of the blood experimentally, numerically, or through various simulations over the years. It focuses on how machine learning platforms derive outputs based on mass and momentum conservation to predict the velocity and pressure profile, analyzing various cardiac diseases for clinical applications. This will pave the way toward responsive AI in cardiac healthcare, improving productivity and quality in the healthcare industry. The paper shows how CFD is a vital tool for efficiently studying the flow in arteries. The review indicates this biomedical simulation and its applications in healthcare using machine learning and AI. Developing AI-based CFD models can impact society and foster the advancement towards responsive AI. [ABSTRACT FROM AUTHOR]

Nowadays, there is an increasing demand for buildings that offer ideal ventilation and thermal conditions, particularly in hot-arid regions. Courtyards emerge as pivotal elements facilitating enhanced airflow and utilizing natural energy, resulting in reducing energy consumption in addition to controlling the pressure created by the wind. In response to the motivation of optimizing building performance in the face of harsh environmental challenges, our study aims to investigate how different courtyard orientations affect airflow patterns and ventilation performance in an educational building model located in Cairo and Delta region. The building, designed for the Pre-university education phase by the General Authority for Educational Buildings (GAEB), as a free-running building. Using a Computational Fluid Dynamics (CFD) simulations through ANSYS-Fluent software, we performed a parametric analysis testing four different orientations (0°, 15°, 30°, and 45°) in the northwest direction to identify the optimal orientation for enhancing ventilation performance. The results consistently indicated that the 0° scenario yielded the best results, followed notably by the 15° scenario which outperformed others by demonstrating superior airflow patterns and pressure differences conducive to enhanced ventilation rates. The 45° scenario was identified as the least favorable result among the four scenarios. These findings provide valuable methodological insights for architects and policymakers seeking to optimize natural ventilation strategies within Egypt's climates.

Abstract The implementation of the Gob-Side Entry Retaining Mining Mode with Roof Cutting and Pressure Relief (GERRCPR) results in the gob connecting to the retaining roadway, creating an open space that causes significant air leakage and increases the risk of spontaneous combustion. A study was conducted during the implementation of the GERRCPR in the Xiaonan Coal Mine N1-1502 working face to investigate spontaneous combustion characteristics, along with fire prevention and extinguishing measures. To analyze gob airflow, Computational Fluid Dynamics (CFD) was employed to collect data on airflow conditions, O2 concentration, and temperature. Based on this, this study focuses on exploring the effects of nitrogen injection treatment under various rates and positions to optimize parameters for buried pipe nitrogen injection. Results indicated that within the GERRCPR, air leakage in the gob increased, leading to an increase in O2 concentration, expansion of the oxidation zone, and an elevated risk of spontaneous combustion. Air leakage primarily occurred from the retaining roadway and the working face near the intake-air roadway, peaking at a retaining roadway length of 500 m, with a flow rate of 226 m3/min. Following nitrogen injection treatment, the oxidation zone was significantly reduced, with optimal treatment achieved at a nitrogen injection depth of 70 m and a rate of 600 m3/h. Field monitoring data showed that the inertization measure of using porous long pipes, a nitrogen injection spacing of 30 m, and a nitrogen injection rate of 600 m3/h significantly decreased the O2 concentration within the gob. This reduction meets safety production requirements and outperforms the effectiveness of traditional buried-pipe nitrogen injection methods, thereby validating the simulation accuracy. Understanding the laws governing spontaneous coal combustion in the GERRCPR and enacting preventive measures for nitrogen injection can improve safety standards in mining operations. This proactive approach can effectively prevent spontaneous coal combustion accidents, resulting in substantial social benefits.

Hydrodynamic separators are commonly used to control the total suspended solid concentration in stormwater before being discharged to natural water bodies. The separator studied in this paper, featuring a swirling flow generated by tangential inlet and outlet connections, was analyzed for its sediment removal efficiency in relation to sediment and flow rates. For the separator studied in this paper, the numerical model showed that the flow field was favorable for the sediments to gather at the center and settle. A higher flow rate or a smaller sediment diameter corresponded to a lower removal rate and vice versa. The dimension improvement for increasing the sediment removal rate was also studied. It was found that increasing the diameter of the separator showed a higher sediment removal rate compared with corresponding increase in the height of the separator. A dimensionless parameter J was proposed to assess the sediment removal rate of a separator, which may be used for designing and optimizing such a device. The removal rate is positively correlated with the J value. When the J value reaches 0.5 or above, the sediment removal rate exceeds 80%, which is a good initial target value for designing this type of separator. HIGHLIGHTS Provided an experimentally validated computational fluid dynamics model.; Changing the diameter has a greater impact on the removal rate of hydrodynamic separators than changing the height.; The J value can be used to evaluate the solids removal efficiency of a hydrodynamic separator.;

Achieving high fluidization quality and bed stability is a paramount challenge in pulsed fluidized beds. 2D hydrodynamics models were studied using the Eulerian-Eulerian method with KTGF. This study investigates the impact of rectangular pulsation superimposed on steady airflow, while maintaining a constant temporal average gas velocity, on fluidization quality. Numerical results indicated that superimposing pulsations on steady airflow and increasing the steady airflow velocity to three times the minimum fluidization velocity resulted in a decrease in the bed expansion ratio. This decrease was most notable particularly at a pulsation frequency of 0.05Hz, with a reducing of approximately by about 21%. By decreasing the velocity ratio from 9.52 to 6.52, the pressure drop increased by 27% and 4.5% at 0.05 Hz and 10 Hz, respectively. Additionally, the fluidization index increased by 32% and 2% under these conditions. The optimal range of pulsed airflow velocity fell between 2.76 and 1.17 times the steady airflow velocity and was most effective at 0.05 – 0.1 Hz.

A solid oxide fuel cell (SOFC) is a clean and very efficient electrochemical conversion device, which generates electricity directly from fuel electrochemical oxidation. In this paper, a three dimensional numerical model has been developed in order to analyse the role of some thermophysical and morphological parameters on the performance of the SOFC cell. In particular, we studied the effect of the variation of permeability of the electrodes: fuel distribution, ionic and electric current density, pressure and diffusion flux are analyzed and compared. The volume fraction of the ionic and electronic phase in the electrodes is studied using a parametric study. It was shown that the current density enhanced by decreasing the permeability, up to a defined value, and it diminished with very small permeability. A remarkable influence of pressure and diffusion of species on the performance of the cell, with the variation of permeability, has been recognized. Varying the permeability in the active layer of electrodes has a large impact on the current density, connected to the volume fraction of ionic phase. This study permits to comprehend the relationship between the performance and microstructure of SOFCs. Meanwhile, it furnishes theoretical guidance for an optimum design of the electrode permeability. • A three-dimensional model of a single SOFC is developed using CFD method. • Varying the permeability of electrode components affects the cell performance. • The impact of volume fractions for different permeabilities is studied. • It is concluded that there is an optimum design of the electrode permeability. [ABSTRACT FROM AUTHOR]

Water scarcity is a global challenge, underscoring the importance of efficient water resource management. Solar stills offer a cost-effective method to convert brackish water into potable water but face productivity limitations. This study aims to enhance solar still productivity through modifications using different fin materials and water depth. Computational Fluid Dynamics (CFD) simulations were employed to evaluate thermal performance across four scenarios: copper and aluminum fins at water depths of 20 mm and 40 mm. Key parameters including temperature distributions, friction volume, and fluid velocity were analyzed for each configuration (MSS-I to MSS-IV). Energy and exergy efficiencies were also assessed. MSS-III, utilizing copper fins at a 20 mm depth, demonstrated the highest daily productivity (8.33 liters) compared to MSS-IV (8.02 liters), MSS-I (7.81 liters), and MSS-II (6.71 liters). Energy efficiencies were highest for MSS-III (60.10%), followed by MSS-IV (57.41%), MSS-I (55.22%), and MSS-II (52.18%). MSS-III also exhibited the highest exergy efficiency (21.50%), with MSS-I (17.15%), MSS-IV (16.43%), and MSS-II (14.12%) following. The study underscores significant improvements in thermal and energy efficiency achieved through specific design modifications of solar stills. MSS-III's higher performance, attributed to the use of copper fins and optimized depth, highlights the critical role of material selection and structural design in enhancing solar still productivity. These findings have important implications for sustainable water resource management, emphasizing the potential of optimized solar still designs to address water scarcity challenges. [ABSTRACT FROM AUTHOR]

The probe chuck is an inspection device assessing the thermal durability of semiconductor wafers in various temperature environments before shipping. It is most important to ensure that the temperature of the chuck upper surface, on which the wafers are placed, is uniform. This study presents an axisymmetric chuck model to improve surface temperature uniformity in both radial and circumferential directions. The local distribution of the flow path height in the axisymmetric chuck was adjusted to make the chuck upper surface with a constant wall heat flux to simultaneously become as uniform temperature as possible. Three optimization algorithms, namely the genetic algorithm (GA), deep q-network (DQN), and actor-critic (AC) were applied. The optimized shape of the flow pathway, improved temperature uniformity, pressure drop, and local heat transfer coefficient profile by three different optimization algorithms are presented in detail. As a result, the surface temperature difference was significantly reduced from 7.137 K in the existing spiral model to 0.682 K. The optimal axisymmetric chuck could reduce surface temperature differences up to 90 % compared with the conventional spiral chuck. [ABSTRACT FROM AUTHOR]

The influence of the forced convection rate on the chemical structure of a polymethyl methacrylate (PMMA) flame in an oxidizer flow under microgravity conditions was studied using numerical modeling. Gas flow around a solid sphere was simulated using the full Navier–Stokes equations for a multicomponent mixture. A multistep chemical kinetic mechanism was considered in the gas phase. The heat transfer and radiation in both the condensed and gas phases were considered in the modeling. On the PMMA surface, the pyrolysis reaction leading to the transformation of fuel from the condensed phase to the gas phase is specified. The forced convection speed varied in the range from 3 to 20 cm/s. Analysis of CO2 concentration fields near the burning surface under microgravity conditions showed that the maximum CO2 concentration is observed in the downstream zone. The width of the flame zone and its chemical structure depend on the intensity of forced convection. The width of the flame against the flow decreases, and the maximum CO concentration increases as the forced convection rate increases. Analysis of the rates of fuel consumption reactions showed that at a low convection speed (vst=3 cm/s), the reaction with the H radical, which has the highest diffusion coefficient, plays a crucial role in MMA oxidation. [ABSTRACT FROM AUTHOR]

Accurate measurement of heterogeneous reaction kinetics in thermogravimetric analysis (TGA) requires accurate estimation of concentration and temperature in the sample. However, this information is difficult to estimate during the measurement, especially at high temperatures and pressures. Computational Fluid Dynamics (CFD) is used to perform a comprehensive analysis of the temperature and species distribution throughout a high‐temperature, high‐pressure test rig, including temperature and species transport within the probe sample. The temperature and gas concentration within the sample are accurately calculated by CFD, providing a much deeper insight into the local temperature and species distribution. The numerical results show a significant decrease in gas concentration and temperature in the core region of the packed bed, indicating that bed diffusion dominates the overall conversion for the char reaction studied in this article. The re‐evaluation based on the model considers the limitations of heat and mass transfer at each measurement point. This forms the basis for a novel, model‐driven approach that derives heterogeneous kinetics from TGA measurements with significantly improved accuracy and reliability. [ABSTRACT FROM AUTHOR]

Wire electrical discharge machining (WEDM) is a non-conventional machining process renowned for precision in machining complex profiles, especially in high-strength and hard materials. This process also found other functions in machining cylindrical workpieces, known as wire electrical discharge turning (WEDT). The material removal mechanism of this process is based on electrical discharges, and evaluating the productivity of the continuous process to a great extent depends on the material removal of individual single discharges. In order to study the influence of rotational speed in material removal of erosion in cylindrical workpieces, theoretical and experimental studies of each single spark are necessary. This comprehensive study delves into the influence of rotational speed in WEDM processes applied to cylindrical workpieces. The research includes a series of single discharge experiments, and introduces a computational fluid dynamics (CFD) thermal model. The developed thermal model demonstrates the capability to predict the material removal rate of a single discharge with an error of 8.6% relative to experimental data. Furthermore, the investigation extends to continuous erosion studies, analyzing the material removal rate under varying rotational speeds. The overall material removal rate decreases 13% due to the declining material removal rate of each single discharge. Additionally, a removal efficiency parameter of erosion of cylindrical workpieces is introduced to provide an evaluation of the process and the influence of crater overlaps. The removal efficiency for various rotational speeds ranges between 22 and 24%, influenced by the proportion of normal discharges and the efficiency of crater overlaps. [ABSTRACT FROM AUTHOR]

The field of nitric oxide (NOx) production combined with turbulent flow is a complex issue of combustion, especially for the different time scales of reactions and flow in numerical simulations. Around this, a series of approach methods, including the empirical formula approach, the computational fluid dynamics (CFD) approach coupling with an infinite rate chemical reaction, the chemical reaction networks (CRNs), and the CFD approach coupling with CRNs, were classified, and we discussed its advantages and applicability. The empirical-formula approach can provide an average range of NOx concentration, and this method can be involved only in special scenarios. However, its simplicity and feasibility still promote practical use, and it is still widely applied in engineering. Moreover, with the help of artificial intelligence, this method was improved in regard to its accuracy. The CFD approach could describe the flow field comprehensively. In compliance with considering NOx formation as finite-rate chemical reactions, the NOx concentration distribution via simulation cannot match well with experimental results due to the restriction caused by the simplification of the combustion reaction. Considering NOx formation as a finite-rate chemical reaction, the CRNs approach was involved in CFD simulation, and the CRNs approach could forecast the NOx concentration distribution in the flow field. This article mainly focuses on the simulation method of nitric oxide (NOx) production in different combustion conditions. This review could help readers understand the details of the NOx formation mechanism and NOx formation prediction approach. [ABSTRACT FROM AUTHOR]

As an essential part of hydrogen removal system in nuclear power plants, PARs could effectively eliminate released hydrogen and prevent potential hydrogen combustion during severe accidents. Serving as a basic composition in the catalytic section of PARs, catalytic element has a direct influence on the hydrogen removal capability of the PAR device. The CFD software STAR-CCM+ was utilized to develop models of catalytic channels containing three common catalytic elements (including catalytic plates, catalytic cylinders, and catalytic spheres). The elementary reaction mechanism was employed as the reaction kinetics model to define the chemical reaction process. This paper aims to evaluate the hydrogen removal capability of the catalytic elements in same operating conditions and analyze important factors for designing the structure of catalytic elements. All the catalytic surface area of catalytic elements was set to 0.045 m2 and inlet boundary conditions were settled identically. Our findings show that catalytic sphere exhibits the best hydrogen removal capability, which is attributed to the large lower half catalytic surface area of spheres. Catalytic plate with a lower height also demonstrates excellent hydrogen removal capability because of the presence of a larger catalytic area in the leading section. However, the hydrogen removal capability of catalytic cylinder is affected by the boundary layer separation vortex. A noticeable decrease in reaction rate occurs on the lower part of the sidewall surface, especially in the catalytic cylinder with a larger radius. In the structure design of catalytic elements, enlarging the catalytic surface area in the leading section and avoiding boundary layer separation on the catalytic surface are essential to further improve the hydrogen removal capability. • Investigation on hydrogen removal capability of common catalytic elements. • Catalytic sphere exhibits the best hydrogen removal capability. • Enlarging catalytic surface area in the leading section eliminate more hydrogen. • Boundary layer separation retards the hydrogen removal rate. [ABSTRACT FROM AUTHOR]